The invention relates to a double seat valve with a leakage control and two valve discs which are displaceable independently of each other, in which one of the valve discs of a smaller outside diameter than the other, is abutable after moving through a predetermined distance in opening direction against the other and forming with the latter a chamber from which a leakage fluid conduit extends to the open air, and wherein the displacement rod of the larger valve disc extends through the tubular displacement rod of the smaller valve disc, and in which both displacement rods form a stroke assuring means and a spring abutment.
Such a double seat valve is for instance known from the German Auslegeschrift No. 2 632 587. In this known construction the end of the hollow displacement rod, which concentrically surrounds the other displacement rod and which extends upwardly from the valve housing, is formed outside the valve housing as a connecting piece which accommodates the lower connection face for connecting the stroke assuring means and a spring abutment. The actual main displacement rod extends from this connecting piece to a displacement cylinder located thereabove. By sandwiching the connecting piece with the stroke assuring means and spring abutment between the actual valve housing and the displacement mechanism located thereabove, a large overall height is necessarily produced, which is connected with considerable disadvantages, especially if a double seat valve of this type is used in a valve complex or even at other places where a low overall height is desirable.